X-Authentication-Warning: delorie.com: mail set sender to djgpp-bounces using -f
Date: Wed, 2 Sep 2009 10:48:58 -0400
Message-Id: <200909021448.n82EmwgV030959@envy.delorie.com>
From: DJ Delorie <dj AT delorie DOT com>
To: djgpp AT delorie DOT com
In-reply-to: 
	<850b568b-640c-435e-b6ca-deb8953ef1d5 AT y10g2000prf DOT googlegroups DOT com>
	(message from dirw on Wed, 2 Sep 2009 07:32:31 -0700 (PDT))
Subject: Re: How to access 0xFF800000 data ?
References:  <850b568b-640c-435e-b6ca-deb8953ef1d5 AT y10g2000prf DOT googlegroups DOT com>
Errors-To: nobody AT delorie DOT com


> I try to use DJGPP to write an utility to flash BIOS.
> In the DJGPP, how to read/write 0xFF800000 data ?
> if possible, could you please show me a sample ?
> Thanks for your great help.

You don't say if you want 0xff800000 linear (just under the 4Gb mark)
or 0xff800000 as a turbo-c "far pointer (FF80:0000 or just under the
1Mb mark).

Look in <sys/farptr.h> if you've allocated a selector for that area
(use DPMI to allocate selectors).

Look in <sys/nearptr.h> if it's performance critical.

Else look in <sys/movedata.h> for generically accessing memory below
the 1Mb boundary.